The present invention refers to measuring of optical parameters of optical devices.
It is an object of the present invention to provide an improved measurement. The object is solved by the independent claim. Preferred embodiments are shown by the dependent claims.
Providing a temperature signal and associating said temperature to the measured optical parameters allows a temperature depending evaluation of the optical parameters. An evaluation taking into consideration the temperature of the respective DUT improves the performance, the reproducibility and the reliability of the measurement.
In the context of the present invention only optical parameters shall be referred to as xe2x80x9cparameterxe2x80x9d, with temperature being explicitly excluded.
Since the measuring instrument is adapted to perform a real-time measurement of the parameters and the temperature, there can be created a very close relationship and in particular a definite association between the values of the parameters and the temperatures. This conjunction between parameters and associated temperature also allows an evaluation of the dependency of the parameters on the temperature.
Some characteristics of optical filters depend on temperature. For example a center wavelength of a specific type of filter, e.g. an arrayed waveguide, can be adjusted by varying temperature. With help of the invention it is possible to automatically determine the optimal operation temperature of the respective filter and to automatically characterize the filter (by measuring its parameters) at its optimal operation temperature.
As mentioned above the optical characteristics of optical devices generally depend on temperature. Thus draught, e.g. caused by opening a door of a room in which the measurement takes place, may lead to a noticeable change of temperature and therefore to falsification of the measurement. With help of the invention the measurement results are comparable and reproducible.
According to a preferred embodiment the measuring system comprises a heating and/or cooling device and/or at least one interface for connecting such a heating and/or cooling device to the measuring system. This heating and/or cooling device is provided for an active control of the temperature of the DUT to be measured. The measurement instrument is directly or via the interface connected to the heating and/or cooling device and is adapted for controlling it such that the heating and/or cooling device prior to the measurement adjusts a predetermined temperature at the DUT and during the measurement observes the predetermined temperature at the DUT. With help of such a heating and/or cooling device it is possible to perform the measurement within a predetermined range of admissible temperatures or nearly exactly at a predetermined optimum temperature. Keeping the temperature at a predetermined level improves the performance of the measurement.